JP7309482B2 - Lens device and imaging device - Google Patents

Description

The present invention relates to a lens device used in imaging devices such as digital cameras and digital video cameras.

In order to appropriately perform image processing such as distortion aberration correction, it is necessary to accurately transmit the position information of the lens device to the imaging device. In particular, in the case of a zoom lens, since distortion changes greatly depending on the zoom position, it is important to detect information on the zoom position with high accuracy. Japanese Patent Application Laid-Open No. 2002-200003 discloses a method of complementing and generating correction data in order to suppress discontinuous changes in image processing when the position of the lens changes.

JP 2013-123121 A

However, in the method disclosed in Patent Document 1, a delay occurs when switching the correction data, so that processing shifts and delays are likely to occur. In addition, the correction data needs to be complemented by the camera, and the effect cannot be obtained with a camera that does not support the complementation process.

On the other hand, if a high-resolution detection device is provided inside the lens device in order to increase the detection resolution of the zoom position, the cost and installation space will increase, resulting in an increase in the price and size of the lens device.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a lens device and an image pickup device which are low in cost and small in size and which can increase the detection resolution of the zoom position.

A lens device as one aspect of the present invention includes an operation member that can be operated by a user for zooming, a zoom lens that performs zooming according to the operation of the operation member, and detection means that detects the zoom position of the zoom lens. Dist (%) is the amount of distortion, N is the maximum division number of the detection means in the entire zoom range from the wide-angle end to the telephoto end, θ (degrees) is the total rotation angle of the operation member , and When the rotation angle of the operation member corresponding to the minimum resolution of the detection means is Δθ (degrees),
Dist<−8.0
In the zoom range that satisfies the following conditional expression,
(N*Δθ)/θ<0.50
satisfies the following conditional expression.

An imaging device as another aspect of the present invention has an imaging device and the lens device.

Other objects and features of the invention are described in the following embodiments.

According to the present invention, it is possible to provide a low-cost, compact lens device and imaging device capable of increasing the detection resolution of the zoom position.

1 is a block diagram of an imaging device according to each embodiment; FIG. 4 is a graph showing the relationship between the sensor output ratio and the rotation angle ratio in Embodiment 1. FIG. 4 is a graph showing the relationship between the sensor output ratio and the value of N*Δθ/θ in Embodiment 1. FIG. 4 is a graph showing the relationship between the sensor output ratio and the amount of distortion in Embodiment 1. FIG. 7 is a graph showing the relationship between the sensor output ratio and the amount of distortion change in Embodiment 1. FIG. 9 is a graph showing the relationship between the sensor output ratio and the rotation angle ratio in Embodiment 2. FIG. 9 is a graph showing the relationship between the sensor output ratio and the value of N*Δθ/θ in Embodiment 2. FIG. 9 is a graph showing the relationship between the sensor output ratio and the amount of distortion in Embodiment 2. FIG. 10 is a graph showing the relationship between the sensor output ratio and the amount of distortion change in Embodiment 2. FIG. 10 is a graph showing the relationship between the sensor output ratio and the rotation angle ratio in Embodiment 3. FIG. 10 is a graph showing the relationship between the sensor output ratio and the value of N*Δθ/θ in Embodiment 3. FIG. 10 is a graph showing the relationship between the sensor output ratio and the amount of distortion in Embodiment 3. FIG. 14 is a graph showing the relationship between the sensor output ratio and the amount of distortion change in Embodiment 3. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the imaging apparatus according to this embodiment will be described. FIG. 1 is a block diagram of an imaging device (imaging system) 300. As shown in FIG. The imaging device 300 includes an imaging device main body (camera main body) 200 and a lens device (interchangeable lens) 100 detachable from the imaging device main body 200 . However, the present embodiment is not limited to this, and can also be applied to an imaging device in which an imaging device main body and a lens device are integrally configured.

The lens device 100 includes a zoom ring (operation member) 1, a lens unit (imaging optical system) 2, a cam (drive mechanism) 3, a zoom position detection sensor (detection means) 4, a memory (storage means) 5, a lens MPU (control means) 6 and a lens communication unit 7. The imaging device main body 200 has a camera communication section 8 , an imaging device 9 , a camera MPU (control means) 10 , a display device 11 and a memory (storage means) 12 .

A zoom ring 1 is an operation member that can be operated (manually operated) by a user for zooming. The lens unit 2 is a zoom lens that forms an object image on the imaging surface of the imaging device 9 . Zooming is performed by changing the arrangement of the lenses constituting the lens unit 2 according to the operation (rotational operation) of the zoom ring 1 . A lens 2a included in the lens unit 2 moves in a direction along the optical axis OA (optical axis direction) during zooming. The cam 3 is a driving mechanism for converting rotational driving of the zoom ring 1 into rectilinear driving of the lens 2a. A memory 5 stores aberration correction information for the lens unit 2 .

The lens MPU 6 acquires aberration correction information from the memory 5 and transmits it to the camera MPU 10 via the lens communication section 7 and the camera communication section 8 . The lens MPU 6 also transmits information indicating the current zoom position to the camera MPU 10 via the lens communication section 7 and the camera communication section 8 . The information indicating the current zoom position is determined based on the output signal from the zoom position detection sensor 4 that detects the zoom position, and is information indicating where the current zoom position is within the entire zoom range. .

The zoom position detection sensor 4 detects the movement amount (straight driving amount) of the lens 2a, and outputs a signal corresponding to, for example, a value indicating how many times the entire zoom range is divided into N equal parts. In this embodiment, the shape of the cam groove of the cam 3 is designed so that the relationship between the rotational operation of the zoom ring 1 and the output signal of the zoom position detection sensor 4 satisfies a predetermined conditional expression.

The imaging device 9 has a CMOS sensor or a CCD sensor, photoelectrically converts an optical image (object image) formed via the lens unit 2, and outputs image data (captured image). The camera MPU 10 uses the aberration correction information corresponding to the current zoom position among the aberration correction information acquired from the lens MPU 6 to correct the aberration of the captured image. At least, distortion (hereinafter, "distortion" may be simply referred to as "distortion") is corrected. The camera MPU 10 displays the corrected image on the display device 11 or stores the corrected image in the memory 12 .

Next, the lens device 100 according to each embodiment will be described with reference to FIGS. 2 to 13. FIG. In order to appropriately perform image processing such as distortion correction, it is necessary to accurately transmit the zoom position in the lens device 100 to the imaging device body 200 . In particular, when the lens 2a is directly moved via the cam 3 by rotating the zoom ring 1, it is possible to perform the zoom operation at high speed or low speed depending on the operation of the zoom ring 1. . When the zoom operation is performed at high speed, if the detection accuracy of the zoom position (zoom position information) of the lens device 100 is insufficient and the distortion changes greatly, the correction value for image processing such as distortion correction is not switched smoothly. It is easy to notice especially in video shooting. Therefore, in the present embodiment, the zoom position detection resolution per unit rotation angle of the zoom ring 1 is appropriately set around the zoom position where the amount of change in distortion of the zoom lens 2 is large in the entire zoom range.

FIG. 2 shows a sensor output ratio indicating the ratio of the output value of the zoom position detection sensor 4 to the maximum division number N of the zoom position detection sensor 4 and the rotation angle of the zoom ring 1 with respect to the total rotation angle of the zoom ring 1 in the first embodiment. is a graph showing a relationship with a rotation angle ratio. In FIG. 2, the horizontal axis indicates the sensor output ratio, and the vertical axis indicates the rotation angle ratio. As shown in FIG. 2, in a region where the sensor output ratio is close to 0, the sensor output ratio is larger than the rotation angle ratio.

FIG. 3 is a graph showing the relationship between the sensor output ratio and the value of N*Δθ/θ in the first embodiment. where N is the maximum division number of the zoom position detection sensor 4 over the entire zoom range from the wide-angle end to the telephoto end, θ (degrees) is the total rotation angle of the zoom ring 1, and Δθ (degrees) is the zoom position detection at each zoom position. This is the rotation angle of the zoom ring 1 corresponding to the minimum resolution of the sensor 4. FIG. "*" means multiplication. In FIG. 3, the horizontal axis indicates the sensor output ratio, and the vertical axis indicates the value of N*Δθ/θ.

FIG. 4 is a graph showing the relationship between the sensor output ratio and the amount of distortion Dist (%) in the first embodiment. In FIG. 4, the horizontal axis indicates the sensor output ratio, and the vertical axis indicates the amount of distortion. The lens device 100 of this embodiment satisfies the following conditional expression (2) in a zoom range (zoom position) having a distortion amount Dist(%) that satisfies the following conditional expression (1).

Dist<−8.0 (1)
(N*Δθ)/θ<0.50 (2)
Conditional expressions (1) and (2) indicate that the detection resolution of the zoom position should be increased in the range of negative distortion where the amount of change in distortion tends to be relatively large. The range of conditional expression (1) is often the wide-angle end side of the zoom lens.

Conditional expression (1) defines the amount of distortion (%). Satisfying conditional expression (1) eliminates the need to correct negative distortion only with the lens system. Therefore, it is possible to reduce the number of lenses arranged on the object side where the lens diameter tends to be large, which is required for distortion correction. On the other hand, if the amount of distortion is set within the range of conditional expression (1), the absolute value of the amount of distortion is large, so the amount of change in distortion during the zoom operation tends to be large. Conditional expression (2) expresses the relationship between the minimum resolution of the zoom position detection sensor 4 and the rotation angle. By satisfying the conditional expression (2), it becomes possible to increase the sensor output ratio per rotation angle (increase the detection resolution) as opposed to the case where the relationship between the rotation angle ratio and the sensor output ratio is proportional. , the zoom position can be detected with high accuracy.

FIG. 5 is a graph showing the relationship between the sensor output ratio and the amount of distortion change. In FIG. 5, the horizontal axis indicates the sensor output ratio, and the vertical axis indicates the amount of distortion change. As shown in FIG. 5, the distortion change is kept small in areas where the amount of distortion is large. As a result, even when the zoom operation is performed under the condition that the distortion changes greatly, it is possible to switch the correction value of image processing such as distortion correction smoothly and accurately.

Preferably, the following conditional expression (2a) is satisfied in the zoom range of the distortion amount Dist (%) that satisfies the following conditional expression (1a).

Dist<−9.0 (1a)
(N*Δθ)/θ<0.45 (2a)
More preferably, the following conditional expression (2b) is satisfied in the zoom range of the distortion amount Dist(%) that satisfies the following conditional expression (1b).

Dist<−10.0 (1b)
(N*Δθ)/θ<0.40 (2b)
In this embodiment, more preferably, at least one of the following conditional expressions (3) to (5) is satisfied.

|DistA−DistB|<0.08 (3)
N<1100 (4)
θ>55 (5)
In conditional expression (3), the amount of distortion before operation of the zoom ring 1 corresponding to the minimum resolution of the zoom position detection sensor 4 is DistA, and the amount of distortion after operation is DistB. The lens device 100 satisfies conditional expression (3) over the entire zoom range. Conditional expression (3) defines the amount of distortion change per minimum resolution of the zoom position detection sensor 4 . By satisfying the conditional expression (3), the amount of change when the correction value for distortion correction or the like is switched becomes small, and smooth aberration correction can be performed regardless of the operation speed of the zoom ring 1 . Exceeding the upper limit of conditional expression (3) is not preferable because it becomes difficult to perform such smooth aberration correction.

Conditional expression (4) defines the maximum division number N of the zoom position detection sensor 4 from the wide-angle end to the telephoto end. Exceeding the upper limit of conditional expression (4) is not preferable because the cost of the zoom position detection sensor 4 increases and the installation space increases, leading to an increase in the price and size of the lens device 100 .

Conditional expression (5) defines the total rotation angle of the zoom ring 1 from the wide-angle end to the telephoto end. If the lower limit of conditional expression (5) is not reached, the total rotation angle of the zoom ring 1 is small, so the amount of change in the zoom position per change in unit rotation angle of the zoom ring 1 increases, and zooming can be performed smoothly. It is not preferable because it becomes difficult.

Preferably, the numerical ranges of conditional expressions (3) to (5) are set as the following conditional expressions (3a) to (5a), respectively.

|DistA−DistB|<0.07 (3a)
N<1050 (4a)
θ>75 (5a)
More preferably, the numerical ranges of the conditional expressions (3a) to (5a) are set as the following conditional expressions (3b) to (5b), respectively.

|DistA−DistB|<0.05 (3b)
N<1010 (4b)
θ>95 (5b)
Moreover, preferably, the following conditional expression (7) is satisfied in the zoom range of the distortion amount Dist(%) that satisfies the following conditional expression (6).

Dist>4.0 (6)
(N*Δθ)/θ<0.90 (7)
Conditional expression (6) defines the amount of distortion. Satisfying conditional expression (6) enables a design that allows for positive distortion, making it easier to shorten the total length of the lens unit (zoom lens) 2, especially in the telephoto range, and shorten the focal length of each group. Easier to configure. On the other hand, if positive distortion is corrected by image processing, it is necessary to perform a process of stretching the center of the screen with respect to the peripheral part of the screen.

Conditional expression (7) expresses the relationship between the minimum resolution of the zoom position detection sensor 4 and the rotation angle. By satisfying the conditional expression (7), the zoom position can be accurately detected by increasing the sensor output ratio per rotation angle, as opposed to the case where the relationship between the rotation angle ratio and the sensor output ratio is proportional. , image processing (electronic aberration correction) such as distortion correction can be performed appropriately. If the upper limit of conditional expression (7) is exceeded, it becomes difficult to appropriately perform image processing (electronic aberration correction), which is not preferable.

FIG. 6 is a graph showing the relationship between the sensor output ratio and the rotation angle ratio in the second embodiment. FIG. 7 is a graph showing the relationship between the sensor output ratio and the value of N*Δθ/θ in the second embodiment. FIG. 8 is a graph showing the relationship between the sensor output ratio and the amount of distortion in the second embodiment. FIG. 9 is a graph showing the relationship between the sensor output ratio and the amount of distortion change in the second embodiment.

10 is a graph showing the relationship between the sensor output ratio and the rotation angle ratio in Embodiment 3. FIG. FIG. 11 is a graph showing the relationship between the sensor output ratio and the value of N*Δθ/θ in the third embodiment. FIG. 12 is a graph showing the relationship between the sensor output ratio and the amount of distortion in the third embodiment. FIG. 13 is a graph showing the relationship between the sensor output ratio and the amount of distortion change in the third embodiment.

Tables 1 to 3 show the total rotation angle θ, the amount of distortion Dist, the value DistA−DistB of conditional expression (3), and the value N* of conditional expression (2) for each of the sensor outputs of Embodiments 1 to 3. Δθ/θ is shown.

Each of the embodiments indicates that the detection resolution of the zoom position is increased in the range of negative distortion where the amount of change in distortion tends to be relatively large.

According to each embodiment, it is possible to provide a lens device and an imaging device that are low in cost, small in size, and capable of increasing the detection resolution of the zoom position.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist.

In each embodiment, the memory 5 may store aberration information of the lens unit 2 instead of the aberration correction information of the lens unit 2, for example. When the information stored in the memory 5 is aberration information, the imaging device main body 200 can correct the captured image so as to reduce the aberration.

1 zoom ring (operation member)
2 lens unit (zoom lens)
4 zoom position detection sensor (detection means)
100 lens device

Claims (7)

an operating member operable by a user for zooming;
a zoom lens that performs zooming according to the operation of the operation member;
detection means for detecting the zoom position of the zoom lens;
Dist (%) is the amount of distortion, N is the maximum number of divisions of the detection means in the entire zoom range from the wide-angle end to the telephoto end, θ (degrees) is the total rotation angle of the operation member , and the minimum of the detection means at each zoom position is When the rotation angle of the operation member corresponding to the resolution is Δθ (degrees),
Dist<−8.0
In the zoom range that satisfies the following conditional expression,
(N*Δθ)/θ<0.50
A lens device characterized by satisfying the following conditional expression: Assuming that the amount of distortion before operation of the operation member corresponding to the minimum resolution of the detection means is DistA, and the amount of distortion after operation is DistB, in the entire zoom range,
|DistA−DistB|<0.08
2. The lens device according to claim 1, wherein the following conditional expression is satisfied. The maximum division number N of the detection means is
N<1100
3. The lens device according to claim 1, wherein the following conditional expression is satisfied. The total rotation angle θ is
θ>55
4. The lens device according to any one of claims 1 to 3, wherein the following conditional expression is satisfied. Distortion amount Dist > 4.0
In the zoom range that satisfies the following conditional expression,
(N*Δθ)/θ<0.90
5. The lens device according to claim 1, wherein the following conditional expression is satisfied. 6. The lens apparatus according to claim 1, wherein the operation member is a zoom ring that can be manually operated by the user. an imaging device;
An imaging device comprising: the lens device according to claim 1 .